One day, Singapore Senior Minister went to Thailand and had lobster for dinner with the Thai King. After SM had finished, he asked the King....
SM: Your Highness, what can you do with this lobster shell?
King : We cannot do anything with it, we just throw it away.
SM: Oh, no. In our country, we send it to the factory and produce prawn crackers.
Then SM had an orange. After he had finished, he asked the King.
SM: What can you do with the orange skin?
King : We cannot do anything. We just throw it away.
SM: Oh, no. In Singapore, we send it to the factory and produce orange jam.
Then SM asked for some chewing gum. After he had finished, he put it on the plate and asked the King.
SM: What can you do with the chewing gum?
King: Oh, no. We just throw it away.
SM: In Singapore, we send it to the factory to produce condoms and then send it to Thailand.
SM was about to leave but then the King asked him...
King: What do you do with the condom when you finish using it?
SM: We cannot do anything. We just throw it away.
King: In Thailand, when we finish using the condom, we send it to the factory to produce chewing gum and then send it back to Singapore!!!
And that is the reason why chewing gum is banned in Singapore.